Switching mechanism



May 22, 1934. D. c LARSON SWITCHING MECHANISM Filed June 30 1932 2Sheets-Sheet l FIGI.

5b 78 74 FIGS M CM LM INVENTOR ATTORNEY Y May 22, 1934. D. c. LARSONSWITCHING MECHANISM Filed June 30', 1932 2 Sheets-Sheet 2 FIGS? 3W C2!Lea/um INVENTOR ATTORNEY will Patented May 22, 1934 UNITED STATESSWITCHING MECHANISM David Carl Larson, Yonkers, N. Y., assignor to OtisElevator Company, New York, N. Y., a corporation of New JerseyApplication June 30, 1932, Serial No. 620,169

13 Claims.

The invention relates to electromagnetic switches and especially toelectromagnetic latching switches for use in elevator control and signalsystems.

In elevator installations in which signalling systems such asannunciators or systems for controlling the lighting of hall lanternsare provided and those in which the slowing down of the car iscontrolled by intending passengers at the landings, the operationdesired may be had through the utilization of one or moreelectromagnetic latching switches for each floor served by the car. Suchswitch usually comprises an electromagnet coil energizable to move theswitch contacts to engaged condition, a latch for maintaining thecontacts engaged after deenergization of the operating coil and arestoring coil energizable to release the latch to permit the separationof the switch contacts. Particularly in present day high buildingconstructions, the number of these switches required for such systemsmakes the cost of the switches and the total space occupied by them animportant factor.

The principal object of the invention is to provide an electromagneticlatching switch which is of compact construction and which may becheaply manufactured and installed.

One feature of the invention resides in the provision of anelectromagnetic latching switch in which the operating coil and therestoring coil occupy a minimum of space.

Another feature of the invention lies in the provision of a hinge forthe contact lever of a switch which has the advantages of both the knifeedge and hinge pin constructions.

A third feature resides in the arrangement of the terminals for theswitch to facilitate the connecting of like terminals of two or more ofthe switches in parallel.

Another feature resides in the mounting of the switches as units oncross bars of a framework to provide a switchboard containing anydesired number of switches.

Another feature lies in the provision of fiat spring contact members andprotecting means for preventing such members from being displaced fromtheir normal position beyond a certain amount.

Other features and advantages of the inven-- tion will become apparentfrom the following description and appended claims.

In carrying out the invention, the operating coil of the switch isarranged to extend outwardly from the switch base with the restoringcoil immediately beneath the operating coil and at right angles thereto.The operating coil is of a length greater than its diameter while therestoring coil is of a diameter greater than its length. By thisarrangement, the overall space taken up by the coils in a plane parallelto the base of the switch is minimized.

The hinge for the contact lever is constructed of four plates in theform of punchings. These plates are arranged in pairs with the pairs atan obtuse angle. The plates of each pair are secured together with thoseof one pair arranged to form spaced apertures into which prongs formedon one of the plates of the other pair extend. An aperture is formed inthe other plate of the other pair into which a prong on one of theplates of the first pair extends. This provides a rocker construction inwhich any relative movement of the pairs of plates other than a pivotalone is obviated.

Different terminal studs of the switch extend different distances fromthe base of the switch. This facilitates connecting like terminals ofthe switches in parallel when the switches are mounted in a groupinasmuch as like terminals of the switches extend the same distancesfrom the switch bases but a different distance from the bases than otherlike terminals, thus permitting the ready connection of like terminalsby jumpers without interference.

Each switch is provided with a clamp at each end for securing it on apair of spaced bars suitably supported in a frame. Any number of theseswitches may be mounted in this manner to form a switch panel withoutthe use of slates or other insulating panels, thus providing a simpleand economical structure.

Each movable contact is a fiat leaf of spring material mounted on thecontact lever. This lever is provided with a guard for the contactingend of each leaf to prevent the leaf being stressed beyond its elasticlimit.

In the drawings:

Figure l is a side elevation of an embodiment of the switch,illustrating the switch in unlatched condition;

Figure 2 is a front elevation of the same;

Figure 3 is a rear elevation of the same;

Figure 4 is a section taken along line 4-4 of Figure 3, but illustratingthe switch in latched condition;

Figure 5 is a view taken along line 55 of Figure 1, illustrating theswitch in unlatched condition;

Figure 6 is a fragmental detail taken along line 6-6 of Figure 1;

Figure '7 is a fragmental detail of the hinge construction;

Figure 8 is a section taken along line 88 of Figure 7; and

Figure 9 is a schematic representation of the arrangement of a pluralityof the switches in a group and illustrating the manner in which liketerminals of the switches may be interconnected.

Referring to the drawings, the switch is ilcarried by a contact lever 36of insulating malustrated as'provided with three pairs of makingcontacts. The stationary ones of these contacts are mounted on a base 21moulded of insulating material. Each of these stationary contacts, whichhave been designated 22, comprises an elongated contact stud 23 having atungsten tipped contact point 24 secured in a hol drilled in the outerend of the stud. The other end 25 of each contact stud is threaded forthe purpose of securing it to a terminal stud moulded into and extendingthrough base 21. The terminal studs for these contacts are designated26, 27 and 28 and each is provided with a threaded aperture to receive acontact stud.

The movable ones of the switch contacts are terial pivotally mounted onthe frame 31 of the switch, this frame being secured to the base 21.Each of these movable contacts, which have been designated 32, comprisesa leaf spring 33 having a tungsten tipped contact point 34 secured in ahole drilled in the contacting end of the spring. The lower end ofeachspring is arranged in a slot 35 provided in lever where it issecured by a screw 36 and binding nut 37. The bottom of each of theslots slopesinwardly, as shown in 1 Figure 4. The springs are heldagainst the bottom of their respective slots by clamps 38. Each of theseclamps is provided with a hole through which the screw 36 extends andits top portion 40 is bent over at right angles so as to press againstthe spring when the nut is tightened to secure the spring in place.

It is preferred to make the contact. springs of phosphor-bronze. Theupper end of each spring extends through a square shaped aperture 41 in'a guard 42 formed on the end of the contact lever. This arrangementprotects the contact springs by preventing their being moved intopositions where their elastic limit is exceeded. 7

The frame 31 comprises a bracket 43 formed ,With a hinge plate 44 whichextends outwardly from the base. A second hinge plate 45 is arranged ontop of hinge plate 44. These hinge plates are secured together by ascrew 46 as'will be explained later. Plate 45 is maintained in definiteposition with respect to plate 44 by doweling plate 45 into plate 44 asindicated at 47 and 48. The dowels on plate 45 and receiving apertureson plate 44 may be formed by punching. Hinge plate 44 is formed with atransversely extending slot 56 near its outer end. The middle portion ofthe outer end of plate 44 is also cut away, leaving prongs 51 and 52.The end of hinge plate 45 is cut away at the sides back to the rear edgeof slot 50, so as to cover only the portion of slot 50 up to the prongs51 and 52, thus forming holes 53 and 54. A prong 55 formed on the end ofplate 45 extends outwardly therefrom between prongs 51 and 52. A pair ofplates 56 and 57 is secured to contact lever 30 by screws 58. Lugs 66are formed on the contact lever and extend into recesses provided inthese plates to definitely locate the plates with respect to the lever.In addition, plate 57 is doweled into plate 56 at 61 and 62. Plate 56 isformed with prongs 63 and 64 which extend into the holes 53 and 54formed by plates 44 and 45. Plate'57 is provided with an aperture 65into which prong 55 extends. I'he above described arrangement of plates44, 45, 56 and 57 forms a hinge, thus providing a pivotal support forthe contact lever.

The plates 56 and 57 form an armature for an electromagnet 66 mounted onand. extending outwardly from frame 31. This electromagnet, uponenergization, acts through the armature to move the contact lever 30 tocontact making position. The electromagnet comprises a coil 67 arrangedon a core 68. This core comprises a plurality of laminations 70 securedbetween side plates 71 as by rivets 72. At the inner end of the core, afastening link 73 is pivoted between side plates 71. This link isprovided with a threaded aperture 74 into which a screw 75 extends fromthe rear of base 21 to mount the electromagnet. Horns 76 formed by theside plates at the outer end of the core retain the coil on the core.

The bracket 43, in addition to its horizontally extending hinge plate44, comprises a plate 77 which extends upwardly behind cofl 67 and formsa part of frame 31 Behind plate 77 is a base plate 78. Plate 77 isdoweled into plate 78 at 80 and plate 78 is doweled into base 21 at 81and 82. These plates are secured to the base by screw 75, a slot 83being formed in the plates through which side plates 71 and link 73extend. The laminations 70, being wider than the side plates 71 formshoulders which abut against plate 77 as screw 75 is tightened to securethe plates in position. A recess 84 is formed in base 23. to receive theend of core 68.

After the movable contacts havebeen moved into engagement with thestationary contacts, they are latched in engaged position by thecooperation of the latch portion formed on the bottom of the contactlever and a plate 85 hinged to the bottom of plate 78. The latchingportion of contact lever 30 comprises a notch 86 formed'by a lip 87extending inwardly from the bottom of the lever. When the armature ofthe magnet 66 is moved to its attracted position, themovable contactsare moved into engagement' with the stationary contacts before thearmature is brought to a stop. Continued movement of the armature aftercontact engagement is effected results in the movable contacts rubbingacross the stationary contacts, thereby insuring positive contactengagement. Movement of the armature'is stopped, by the engagement oflugs 60 with horns 76, these lugs extending beyond the armature toprevent the armature engaging the core. The contact springs 33 yieldafter the engagement of the contacts takes place, the apertures in guard42 being of suficient size to permit the described operation to takeplace. Just before the armature is brought to a stop, a point is reachedwhere the 7 in the enlarged portion into which plate 78 extends. Therear end of plate 85 is cut away into the slot to form prongs 96. theseprongs extending into recesses 91 formed in base 21.

The hinge for contact lever 30 is at such point that the weight of thelever and parts mounted thereon biases it to its position in "which thecontacts are separated. To release'the contact lever and permit theseparation of the contacts,

plate 85 is moved upwardly out of notch 86 by an electromagnet 92, theplate forming an armature for the electromagnet. The electromagnet issecured to bracket 43 by screw 46. It comprises a coil 93 arranged on acore which extends downwardly from hinge plate 44. This core is movementof thecontact lever.

screw 46 and the bushing to retain the coil on thecore. The tighteningof screw 46 in the assembly' operation clamps the bushing 94 against thebottom of plate 44, thus locking plates 44 and 45together. At the sametime coil 93 is secured to bracket 43, this arrangementplacingrtherestoring coil immediately beneath the operatingrcoiland-atright angles thereto. An aperture 97 isprovided in armature to receivethe head. of screw 46 when the armature is' attracted. With thisconstruction, plates 44 and"45.:form part of the magnetic circuit forboth'the electromagnets 66 and 92.

Upon'energization of electromagnet 92, armature-:85 is moved toattracted position where it isbrought to a stop" by its engagement withwashers 99. As. the upward movement of the armature takes place, itsouter end moves out of:notch.86. This releases contact lever 30 whichis=thereuponreturned to contact separated condition. by theaction ofgravity, aided initially by. the contact springs. A slot 98 is providedin the contact lever to admit the end of armature 852as-2the returnmovement of the contact lever takes-place. The return movement of thelever isbrought to a stop by the engagement of the end 'ofiarmature 85.withthe bottom of slot 98.

A plurality of additional terminal studs 100, 101, 102, 103 104 and 105are moulded into base 21. These studs extend only partially into thebase 'and constitute terminals for the leads from the magnet coils 6'7and 93 and for the movable contacts. 32. The movable contacts areconnected'to their respective terminals by flexible conductors, theconductor, designated 106, for oneof the 'outermovable contacts beingillustratedin Figure 1. This conductor is suitably insulated, as by aprotective covering of carnbrie: tubing, and is provided at each endwith suitableclips for effecting the connection. From the movablecontact, theconductor is led around to the back of lever 30-where itextends upwardly -th-rough a-slot107 provided in the lever and in whichit is held by a clamp 108 securedby screw 36-. From this point, theconductor leads .to-aznotch- 110 formed in the side of the base 21.

Fromithe notch it extends to the terminal stud where it: is secured bysuitable binding nuts. Suflicient bight is provided in the conductorbetween notch' 110 and slot 107 to allow for pivotal The conductorforzthe: other outer movable contact is arranged in: a. similar manner.The conductor for middle movable contact is also arranged in asimilar-manner and is led through the same slot in lever30 as theconductor for one of the outer movable contacts.

The conductors from the magnet coils are led to theirterminal studsthrough wider notches 111 along the sides'of base 21. In elevatorinstallations'in which the switch would be useful for sigsembled:Plates- 44'and 45 are secured together and electromagnet 92 securedthereto by screw 46. Plate 85 is slid over plate 78 and plates 77 and 78and electromagnet 66 are secured to base 21 by screw '75. Plates 56 and57 are secured in hinged relation to plates 44 and'45 and to the contactlever by screws 58. This not only pro? vides' a construction which maybe economically assembled but also one which may be readily and easilytaken apart whenever desired.

During movement of contact lever 30, the outer edge of the bottom ofplate 56 to the sides of the prongs 63 and 64 rocks on plate 44, thusforming.

a knife edge fulcrum for the lever. The arrange ment of prongs andapertures provided by plates 44, 45, 56 and 57 prevents any movement ofthe lever except a pivotal one. Thus akniie edge hinge construction isprovided which requires very little clearance, has little friction andre? quires no lubrication, and at the same time has all the advantagesof the hinge pin construction. In addition, this hinge arrangement isvery economical to manufacture as the plates may all be formed frompunchings.

The coils 67 and 93 are wound with the proper amount of wire to effectthe desired operation of their respective armatures. By making coil 67of a length greater than its diameter and coil 93. of a diameter greaterthan its length, a construction is provided in which the coils occupy a.

minimum overall space in a plane parallel to the base of the switch. Ithas been found that a suitable construction is obtained by making thediameter of the restoring coil 93 substantially equal to or slightlygreater than the diameter of the operating coil 67 and not to exceed thelength of the operating coil.

The economy of space thus obtained is particularly important where alarge number of switches are mounted in a group. The space taken up bythe switches in a control room is an important factor as may be seenfrom an eighty floor elevator installation, for example, where both anup switch and a down switch is provided for each intermediate floor.

The construction of the switch also admits of mounting the switches sideby side on cross bars, thus not only further economizing on space butalso eliminating the expense of a slate panel. The mounting of a groupof nine switches is illustrated schematically in Figure 9 by way ofexample. The crcss bars, designated 112, extend horizontally betweenuprights (not shown). The switches are arranged between the cross barsand in abutting relation at their sides. noted that this closes thenotches 110 and 111 for the leads from the switch parts to theterminals, thus definitely locating the wires. In this connection, it ispreferred to arrange notches 110 at different points on the two sides ofthe base of each switch, thus causing these notches to be covered by theside of the base of the adjacent switch.

The manner of securing a switch to the cross bars is illustrated inFigures 1, 3 and 4. The

- switch is clamped to the bars at both the top and It is to be providesconvenient access to the switch terminals.

Where these switches are employed as floor relays in an elevator system,as, for example, to control signalling operations or to control theslowing down and stopping of the elevator car, certain'like terminals ofeach switch are connected in parallel relation. Such connections arefacilitated by extending different terminal studs of each switchdifferent distances from the base 21. A suitable arrangement for thispurpose is illustrated in which terminal stud 28 extends outwardly fromthe base a certain distance, terminal stud 26 extends outwardly from thebase a greater distance, and terminal stud 2'7 extends outwardly fromthe base a distance intermediate the distances which terminals 26 and28. extend from the base. Terminals 103, 104 and 105 are simi- 'larlyextended different distances from the base but oppositely in thatterminal 103 extends outwardly the same distance as terminal 28,terminal 104 the same distance as terminal 27 and terminal 105 thesame'distance as terminal 26. Terminals 100 and 102 extend outwardly thesame distance as terminal 2'7, thus providing a similar relationshipbetween terminals 105, 102 and 28, and between terminals 103, 100 and26; Terminal 101 extends outwardly from the base a greater distance thanterminals 100 and 102. Like terminals of each of the other switches areextended outwardly the same distances from their bases. This permits thedesired parallel connections to be effected by jumpers withoutinterference with other jumpers or connectors.

Suitable jumpers for connecting like terminals of the switches areillustrated in Figure 9. The jumpers designated 11'? are for efiectingthe desired parallel connection of like terminals of adjacent switchesin the same horizontal row and extend horizontally between theseterminals, as

illustrated. 'Each of these jumpers comprises two connecting portions118 which extend Vertically from the studs and which are joined by theweb portion 120. These jumpers may be suitably formed by punching themfrom sheet copper. With like terminal studs or" the switches extendingoutwardly from their bases the same distance and with this distancedifferent from V thatwhich other like terminal studs extend from thebases, the jumpers which connect different like terminals are indifferent planes, as may be seen in Figure 6. Thus, a convenientarrangement is provided for interconnecting like terminals of a group ofswitches without interference.! A jumper 121 has been shown connectinglike terminals of the switches in an outer column in vertical alignment.This jumper is of the same construction as jumpers 117 with theexception that the web portion is longer to suit the greater distancebetween the terminals. The vertically extending jumpers are particularlyuseful for connecting like terminals of a group of switches to the liketerminal of one of the outside switches which acts as a feed terminal,the like terminals in each horizontal row being connected as illustratedfor two switches in the bottom row so as to be fed by the verticaljumpers.

Although the invention has been described as applied to a latchingswitch, certain features of the invention are applicable. to other typesof switches.

As many changes could be made in the above construction and manyapparently widely different embodiments of this invention could be madewithout departing from the scope thereof,

it is intended that all matter contained in the above description orshown in the. accompanying drawings shall be interpreted asillustrativeand not in a limiting sense.

What is claimed is:

1. Switching mechanism comprising; a base; a stationary contact securedto said base; a movable contact for engaging said stationary contact; alever carrying said movable contact, said lever being biased to contactdisengaged posi tion; a support extending outwardly from said base atright angles thereto; an armature seemed to said lever and pivotallysecured to said sup port to form a fulcrum for said lever; an electromagnet for attracting said armature to move the lever into contactengaging position, said electromagnet having a core extending outwardlyfrom said base at right angles thereto and a coil on said core, saidcoil having a length greater than its diameter; a latch member pivotallymounted on said base and cooperating with said contact carrying lever,upon attraction of said. armature by said electromagnet, to latch saidcontact carrying lever in contact engaged position; and a restoringelectromagnet arranged be low said operating electromagnet and at rightangles thereto, said restoring electromagnet hav-.' ing a core securedto said support and a coil on said core, said coil having a diametergreater than its length, substantially equal to the diam- 1 eter of thecoil of the operating electromagnet and less than the length thereof,and said restoring electromagnet upon energization acting to attractsaid latch member to release said contact carrying lever to permit itsreturn to contact 1 disengaged position, said contact carrying lever,upon returning to contact disengaged position, being brought to a stopby engaging said latch member.

2. Switching mechanism comprising; a station-' ary contact; a contactspring for cooperating with said stationary contact; an electromagnet;

an armature for said electromagnet for moving said contact spring withrespect to said stationary contact upon being attracted by saidelectromage net; and guarding means for said contact spring to preventits being stressed beyond its elastic limit. l

3. Switching mechanism comprising; an elec tromagnet; an armature forsaid electromagnet; a stationary contact; a leaf contact spring forcooperating with said stationary contact; and apivoted member carryingsaid. contact spring, said member being secured to said armature so asto effect movement of said contact spring with l .1

ver of insulating material carrying said contact spring, said memberbeing secured to said armature so as to effect engagement of the end ofsaid contact spring with said stationary contact upon attraction of saidarmature by said electromagnet and being provided with, an aperture atthe 1 contacting end of said spring through which the W spring extendsso as to prevent movement of the spring into position where its elasticlimit is exceeded.

5. An electromagnetic latching switch compris ing; a vertically disposedbase; an operating magnet having a coil of a length greater than itsdiameter mounted on said base so that its core extends outwardlytherefrom at right angles thereto; a frame of magnetic material mountedon said base so that the body of said frame is parallel to and belowsaid magnet and constitutes the return path for the flux of saidoperating magnet; an armature for said operating magnet pivotallysupported at the outer end of said frame; an operating lever secured tosaid armature and having a portion extending downwardly below the bodyportion of said frame; switch means "actuated by said operating lever; alatch member pivotally supported adjacent said base below the bodyportion of said frame with the outer end of said latch member engagingthe downward extension of said operating lever in the position thereofresulting from 'energization of said operating magnet to maintain saidoperating lever in such position, said latch member being formed ofmagnetic material from its pivot at least to its mid-length; a member ofmagnetic material positioned adjacent said base so as to I provide aflux path from the pivot of said latch member to the body portion ofsaid frame; and a reset magnet having a coil of a diameter greater thanits length mounted on the body portion of said frame at right anglesthereto with the core of said reset magnet extending downwardly so theother to provide an aperture; and a support for said armature formingpart of the magnetic circuit for said electromagnet, said supportcomprising a second pair of superimposed plates, at least one of whichis of magnetic material, said plates being formed to provide spacedapertures to receive said prongs on said one armature plate and a prongto extend into the aperture on the other armature plate, therebyproviding a hinge for said armature.

7. An electromagnetic switch comprising; a

base; an electromagnet secured to said base so that its axis of its coreend is horizontal; and an armature, armature support and armature hingecomprising four plates of magnetic material arranged in pairs with theirfiat sides in contact, one pair forming said armature and the other pairbeing secured to said base and extending horizontally to form a supportfor said armature and a return path for the flux from saidelectromagnet, the supporting pair of plates being formed to providespaced apertures and a prong at the outer end between the sides thereofand the armature pair of plates being formed to provide prongs whichextend into said spaced apertures and an aperture to receive said firstnamed prong.

8. An electromagnetic switch comprising; a vertical base; anelectromagnet secured to said base and extending horizontally therefrom;a pair of plates, at least one of which is of magnetic material,arranged with their fiat sides in contact and secured to said base andextending horizontally therefrom, the flat sides of said plates being inhorizontal planes and forming part of the magnetic circuit for saidelectromagnet, the

lower plate being recessed inwardly from its outer end and formed withnotches extending toward the sides of the plate at the inner end of saidrecess, the upper plate being formed with a prong on its outer endintermediate its sides and extending outwardly to the end of the bottomplate; and an armature for said electromagnet comprising a pair ofplates, at least one of which is of magnetic material, with their flatsides in contact, the inner one of said armature plates being formedwith prongs which extend into said notches, the bottom of said innerplate to the outside of each of its prongs resting on the bottom plateof said first named pair to form a fulcrum, and the outer one of saidarmature plates being formed with an aperture to receive said prong onthe upper plate of said first named pair.

9. An electromagnetic switch comprising; a vertical base; anelectromagnet secured to said base and extending horizontally therefrom;a pair of plates of magnetic material with their fiat sides in contactsecured to said base and extending horizontally therefrom, the fiatsides of said plates being in horizontal planes and forming part of themagnetic circuit for said electromagnet, the lower plate being recessedinwardly from its outer end and formed with notches extending toward thesides of the plate at the inner end of said recess to form prongs, theupper plate covering said recess between said prongs and out to theinner edges of said prongs, thus forming spaced apertures, and beingformed with a prong extending outwardly between the first named prongs;and an armature for said electromagnet for movement through a smallrange of angles all obtuse to said pair of plates, said armaturecomprising a pair of plates of magnetic material with their fiat sidesin contact, the inner one of said armature plates being formed withprongs which extend into said spaced apertures, the bottom of said innerplate to the outside of each of its prongs resting on the bottom plateof said first named pair to form a fulcrum' and being recessed betweenits prongs to clear the upper plate of said first named pair, and theouter one of said armature plates extending at its bottom between saidprongs of the bottom plate of said first named pair and being formedwith an aperture to receive said prong on the upper plate of said firstnamed pair, thereby preventing any substantial movement of said pair ofarmature plates relative to said first named pair of plates except apivotal one through said range of angles.

10. An electromagnetic switch comprising; a magnet having a free coreend; an armature for said magnet for pivotal movement toward and awayfrom said free core end about a horizontal axis below the same, saidarmature at the pivot end thereof being formed with two portions onopposite sides of a common plane passing through said horizontal axisbut displaced from each other along said axis, the inner one of saidarmature portions terminating at said horizontal axis and the outer oneof said armature portions extending beyond said horizontal axis; and asupport for the pivot end of said armature comprising a member ofmagnetic material forming part of the magnetic circuit for said magnetand mounted below said free core end so that said horizontal axis isincluded in said support, said member being formed with two portions onopposite sides of a common plane passing through said horizontal axisbut displaced from each other along said axis, the upper one of saidsupport portions terminating at said horizontal axis against said outerarmature portion and the lower one of said support portions extendingunder and engaging said inner armature portion, whereby pivotal movementof said armature toward and away from said free core end through anglesobtuse to said common plane of said support portions is effected by therocking of the bottom outer edge of said inner armature portion on saidlower support portion and by the rocking of said outer armature portionabout the lower terminal edge of said upper support portion, both saidedges lying in said horizontal axis.

11. An electromagnetic switch comprising; a magnet having a free coreend; an armature for said magnet for pivotal movement toward and awayfrom said free core end about a horizontal axis below the same, saidarmature at the pivot end thereof being formed with two portions onopposite sides of a common plane passing through said horizontal axisbut displaced from each other along said axis, one of said armatureportions being in two parts, one part on either side of the otherarmature portion, the inner one of said armature portions terminating atsaid horizontal axis and the outer one of said armature portionsextending beyond said horizontal axis; and a support for the pivot endof said armature comprising a member of magnetic material forming partof the magnetic circuit for said magnet and mounted below said free coreend so that said horizontal axis is included in said support, saidmember being formed with two portions on opposite sides of a commonplane passing through said horizontal axis but displaced irom each otheralong said axis, one of said support portions being in two parts, onepart on either side of the other support portion, the number of parts inthe lower one of said support portions corresponding to the number ofparts in said outer armature portion, the upper one of saidsupport/portions terminating at said horizontal axis against said outerarmature portion and the lower one of said support portions extendingunder and engaging'said inner armature portion, whereby pivotal movementof said armature toward and away from said free core end through anglesobtuse to said common plane of said support portions is efiected by therocking of the'bottom outer edge of said inner armature portion on saidlower support portion 7 and by the rocking of the said outer armatureportion about the lower terminal edge of said upper support portion,bothsaid edges lying in said horizontal axis.

12. An electromagnetic switch comprising; a magnet having a horizontalcore end; a pair of stationary plates of sheet material secured togetherwith their flat faces in contact, and arranged horizontally below andspaced from said core end, at least one of said stationary plates beingof magnetically responsive material and forming part of the magneticcircuit of said magnet, the outer end of the upper stationary platebeing cut off transversely to form a straight edge of one or moresections and being cut away at one or more places to expose'portions ofthe outer end of the lower stationary plate in alignment with said edge,the outer end of said pair .of stationary plates being cut to provideone or more apertures therethrough, with the outer edge or edges of suchapertures substantially in alignment with said first named edge; anarmature for attraction by said coreend comprising two plates of sheetmaterial secured together with their flat faces in contact, at least oneof said plates being of magnetically responsive material, the pivot endof the inner plate of said armature plates being cut away to clear theportion or. pore tions of said upperstationary plate terminating in saidfirst named edge, so that said first named edge abuts against the innersurface of the outer plate of said armature plates, the pivot end of.

the inner plate of said armature plates also be-: ing cut offtransversely to form a'straightedge' of one or more sections each ofwhich 'abuts,

against an exposed portion of said lower stationary plate and beingformed with one or more prongs each extending into a corresponding oneof said apertures in said pair of stationary plates;

and means confining the motion of said armature to a relatively smallrange of angles all obtuse to said stationary plates so that the weightof said armature is supported by the outer corner of said second namedstraight edge rocking on the exposed portion or portions of said lowerstationary plate, and so that the pressure of said armature due to theattraction of said core end for said armature when said magnet isenergized, is transmitted through the lower corner of said first namedstraight edge about which'rocks said outer armature plate. 7

13. An electromagnetic switch comprising; a magnet having a horizontalcore end; a pair of stationary plates of sheet material secured togetherwith their fiat faces in contact and arranged horizontally in verticalalignment with said core end, at least one of said stationary platesbeing of magnetically responsive material and forming part of themagnetic circuit of said magnet, the outer end of the stationary platenearersaid core end being cut oii transversely to form a straight edgeof one or more sections, being out to form at least one prong extendingbeyond said straight edge and being cut away at one or more places toexpose portions of the outer end'of the-other stationary plate inalignment with said edge, the outer end of said pair of stationaryplates beingcut to provide one or more apertures therethrough, with theouter edge 'or edges of such apertures substantially in alignment withsaid first named edge; and an armaturefor attraction by said core endcomprising two. plates of sheet material secured together with;

their fiat faces in contact, at least one of said plates being ofmagnetically responsive material, the pivot end of the inner plate ofsaid armature plates being cut away to clear the portion or portions ofsaid stationary plate terminating in said first named edge and saidfirst named prong, the pivot end of the outer plate of said armatureplates being formed with an aperture receiving said first named prong sothat said first named edge abuts against the inner surface or" the outerplate of said armature plates, the

pivot end of the inner plate of said armature plates also being out offtransversely to form a straight edge of one or more sections each ofwhich abuts against an exposed portion of said second named stationaryplate and being formed with one or more prongs each extending into acorresponding one of said apertures in said pair of stationary plates,said four plates thereby providing a portion of the magnetic circuit for7 DAVID CARL LARSON.

